We know that many satellites have been launched by different countries for space research.
At first USSR launched her satellite sputanice-1 in 4th October 1957. Then after few weeks sputnik-II satellite was launched.
India launcher her first successful satellite vehicle SLV-3 on 18th July 1980. These use chemical substance which on ignition provide thruster for the rocket to move forward.
These are the chemical substances which on ignition provide thrust for the rocket to move forwarded.
A propellant is a combination of an oreidiser and a full which when ignited under goes combustion to release large quantities of hot gases .The passage of hot gases through the nozzle of the rocket motor provides the necessary thrust for the rocket to move forward according to Newton’s third law of motion i.e. "every action and reaction is equal and apposite".
1. Solid Propellants
2. Liquid Propellants
3. Hybrid Propellants
These are the mixtures of a solid fuel and a solid oxidizer.
These are of two types:
(1) Composite propellants
(2) Double base propellants
(i) COMPOSITE PROPELLANTS
These are solid propellants which use polymeric binder such as polyurethane or poly butadiene as a fuel and solid oxides such as ammonium per chlorate, nitrate or chlorate.
Performance of these propellants can be increased by using some additives such as finely divided magnesium or aluminum metal along with fuel.
(ii) DOUBLE BASE PROPELLANTS
These are solid propellants which mainly use bitingly cerise and nitro cellulose. The nitro cellulose gels in nitroglycerine set in as a solid mass.
The main disadvantage of solid propellants is that these propellants once ignited will routine burning with predetermined rate. These cannot be regulated.
2. LIQUID PROPELLANTS
These are called liquid propel abuts because these are the mixture of liquid oxidizer and liquid fuel. Liquid oxidizers are liquid origin, nitrogen peroxide or nitric acid and liquid fuels are kerosene, alcohol, hydrazine or liquid hydrogen.
These are of two types
(1) Mono propellants
(2) Bipropellants
(i) MONO PROPELLANTS
The propellants in which a single chemical compound act as a fuel oxidizer care called monopropellants, e.g. hydrazine, nitro methane methyl nitrate, hydrogen peroxide, etc.
Except hydrazine, the other compounds contain both the oxidizer and the fuel elements in the same molecule.
(ii) BI-PROPELLANTS
These are propellants in which the fuel and oxidizer are stored separately but are allowed to combine at the time of combustion. E.g. kerosene and liquid oxygen. Etc.
ADVANTAGE OF ILLIQUID PROPELLANTS OVER SOLID PROPELLANTS
(i) The illiquid propellants give higher thrust than solid propellants.
(ii) The thrust generated by liquid propellants can be controlled by switching on and off the flow of propellants. On the other hand, the thrust cannot be controlled in solid propellants.
3. HYBRID PROPELLANTS
These are the propellants which consist of solid fuel and a liquid oxidize. For example, liquid N2O4 (liquid oxidize) and acrylic robber (solid fuel)
Examples of propellants used in different rockets
(I) SATURN BOOSTER ROCKETS of American space programmed used a Minturn of kerosene and liquid oxygen as the propellant in the initial stage whereas liquid oxygen and liquid hydrogen are used as propellant in high altitudes
(ii) Russian rockets such as piton use a liquid propellant consisting of kerosene and liquid oxygen.
(iii) The Indian satellites SLV-3 and ASLV used composite solid propellants.
(iv) The rockets PLSV will use solid propellant in the first and third stages and liquid propellant in second and fourth stages. The liquid propellant will consist of N2O4 and unsymmetrical diethyl hydrazine (UDMH) and N2 O4 and mono methyl hydrazine (M M H) respectively.